When I start my snowblower, I turn the choke fully clockwise to close the butterfly(choke is fully on). I prime it 3-4 times and On the first or second pull it starts.

As it warms up I slowly turn the choke knob counterclockwise to open the butterfly. Unfortunately, I reach max engine rpm at about 2/3 to 3/4 choke opening. I cannot get to full open(choke is off) on the choke. The choke does not have a true on and off spot marked on the engine. There is a sticker indicating a gradation from a small, narrow wedge to a large open wedge (at this end there is a picture of a butterfly valve opened)

Is there something wrong? I have been on a tractor where it would not run if the choke was opened fully. I do not know if this is correct or if the carb is out of adjustment.

The last phyical stop going off choke should be no choke. You can verify that by sticking you finger under the heater cover and against the carborator throat. Feel the buttterfly as you turn the choke knob. The butterfly closed will cover the throat. It's back a bit so you can't feel the butterfly. But as you go to full open it will be parallel to the throat and you should feel the end diameter section of the butterfly gettnig to that position.

If the engine is warm, a few minutes of runtime, the engine should run properly without choke at max throttle and verify that under load. If it does not then the carb probably has some dirt in there and needs to be serviced. A new machine getting clean gas should not need service for several years.

sorry about the choke terminology. I am trying to relate the book to what is really occurring.

The knob opened the butterfly valve. I do this once the engine starts and is warmed up. It will only allow me to open the butterfly valve only so far then it starts to sag, stumble and the dies (progressively as I continue to open the valve slowly)

Is it possible that the choke knob is not positioned properly on the shaft it fits on to? It should come off (pulling by hand or prying with a screwdriver). You could then try to move the shaft all the way to the left by hand or with a screw driver if it has a slot. If that fully opens the choke, then push the knob back on so that it points to the open position.

I'll check that when I get home. To me it seems that I can go past the point on the choke sticker with the knob when rotating it counterclock but it stops on the top of the sticker (butterfly closed) correctly when turned clockwise. I want to make sure that the butterfly is not fully opened at the point I am referring to as 2/3 to 3/4 opened. It could be misaligned.

I checked and it appears that the valve is properly opening and closing and to the right amount. I compared it also, last night, to another unit and the linkage and what not were the same. I guess it will have to go in. My guess is that it needs to allow a bit more fuel in to compensate for the increase in Air to get the fuel/air ration right and this is why it is stalling out at full open on the valve. Either there is a clog in the carb or it needs an adjustment.

Does this sound reasonable or could it be something else? I really feel bad that I just purchased the thing and it needs fixing. Go figure. I get the one off the line with a defect or misadjustment.

Well I got it back and there was some stuff in the carb, not much though. Guys at Four Seasons said the bigger issue is that the manual has an error. This is what is said:

"The choke control is found on the rear of the engine and is activated by rotating the knob clockwise. Activating the choke control closes the choke plate on the carburetor and aids in starting the engine"

Later they tell you to activate the choke and , once warmed up to turn it off. They got it backwards. To turn on the choke, you turn it COUNTER CLOCKWISE.

Well, I was starting it with the choke off ( still started on the first or second pull - very nice) and slowly engagine the choke as it wasmed up. This is why I couldn't go beyond 1/4 rotation.

Hopefully someone at MTD will catch this and update the manual.....

Today it snowed 3-4 inches and I must say, now that I know how to operate it properly, it purred like a kitten. No sputtering or anything. Nice and smooth and not too loud (Unfortunately I do not have a point of reference to other snow throwers but based on other yard equipment, it is not too bad).For only a 5 HP motor, it threw the snow with the deflector a little on about 10-20 ft. I couldn't let it go too far otherwise I would be throwing it into my neighbors driveway. On the other hand, the snow today was light, not our typical wet heavy stuff.

The decal show a curved wedge which is narrowest at the top and widest at the bottom. It curves around the left side of the knob. At the bottom is a picture of a partially opened butterfly valve. To me if I want the valve closed, I would point the knob to the narrowest section, since the picture shows the valve open at the other end, hence I would be turning it clockwise. Unfortunately this too is counter intuitive. I guess the symbol should have been put at the top. At the narrow end and a closed valve at the larger bottom end. They should have labeled one end 'FULL' and the other 'OFF', just like they do in the instructions. Ironically, the manual has the sticker displayed as a mirror image of what is on the machine....